A class of instruments known as speculums facilitates access to the eye during ophthalmic procedures by spreading the lids. Speculums are of many designs but lid speculums work by using a wire or blade to wrap around the eyelid margin several millimeters near the midpoint to spread the eyelids gaining exposure of the ocular surfaces.
Problems with conventional speculums occur when the lid length is short, limiting the distance that the lids can be retracted, or when the eye is deep-set. These two problems lead to a “squaring” of the view and limit the working area and visibility. Additionally the lids tend to rise up when stretched tight, creating a potential space for fluid to pool. Pooling of fluid limits visibility of the surgeon further and allows for bacteria and eye secretions to potentially enter the eye, especially in cataract surgery where a large amount of water is used in the extraction of the lens. Elderly eyes become recessed from the loosening of the fat pads, which further complicates the view with water filling into the space formed by the recession. Cataract surgery is the most common ophthalmic procedure with over a million procedures performed each year.
A tube connected to a suction source at one end and having an opening at the other end can be used to suction water from the surgical site. Such a suction tube is rarely used in ophthalmic procedures as it represents an additional source of obstruction to view and free movement.
Another method to solve the problem of pooling includes a wick of sponge that works slowly by osmosis to provide a drain out of the side of the lid. This passive method is reasonably effective in removing small amounts of fluid but fails in deep-set eyes and the wick often floats out of the eye. Positioning the patient's head to be angled to the side can be helpful but often limits the microscopic view into the eye from obstruction by the nose or brow.
Some lid speculums for opening eyelids have hollow tubing with openings or holes formed therein, the tubing being attached to suction for removal of water or fluids from the orbital/ocular area. These lid speculums can perform aspiration, however, the aspiration is often ineffective because the holes in these speculums are adjacent the lid margin which is often well above the corneal surface, making the holes incapable of removing the water. The poor visibility encountered by the surgeon while operating on a patient increases the risk of a poor surgical outcome. Viewing the eye under water affects the surgeon's view into the eye altering depth perception and magnification. The risk of infection from this water getting into the eye is also increased.
Recently, a popular procedure using ultraviolet laser to reshape the cornea to change the refractive power of the eye was developed. In this procedure the front surface of the cornea is exposed to 193-nanometer (nm) light to remove a precise amount of tissue to change the curvature of the anterior cornea. In a small eye, the problem of fluid clearance is made worse by the tendency of the inner part of the cornea (stroma) to absorb water when the stroma is exposed. Tear film or water from the device (known as a microkeratome and used to open the anterior cornea) quickly absorbs into the inner tissue of the cornea. The water slows the absorption of the 193 nm laser and alters the treatment shape leading to problems with the patient's vision correction including aberrational vision. Currently, wicking methods and aspirating speculums are used but are often inadequate due to the raising of the ports of conventional aspirating speculums above the ocular surface. Wicking dams can be helpful but are often overwhelmed by the tear film. By the time wicking dams are in place the fluid is often already on and in the stromal bed. Manual removal of fluid by employing a sponge necessitates stopping the surgical procedure, which changes the hydration and dehydration of the cornea and reduces the precise standardization required to attain good surgical results for the patient.
Many ophthalmic procedures are performed using topical anesthetic. These drugs are applied as topical drops and are ideally applied under the lids to reach the sulcus, the sulcus being the point under the lid where the covering of the lid and globe fold back on themselves. A sponge can be soaked with anesthetic and placed under the lid to keep the drug from diffusing away in the tear film. These drugs are somewhat toxic to the anterior corneal surface and especially in refractive surgery many surgeons try to avoid drug exposure to the front surface by using a soaked sponge. The topical drugs are fairly short acting, so to add more drugs by conventional topical methods required using a sponge and stopping surgery temporarily to apply additional drugs. Other techniques involve drugs that are injected under the conjunctiva, called peribulbar. The peribulbar techniques largely work by continuous leakage of the drugs out of the wound created. To avoid this peribulbar injection technique, a continuous drug delivery system is desirable. Thus, there is a desire to find another device for applying topical drugs during ophthalmic procedures.
In certain emergency situations, like acid or alkali exposure to the eye, where continuous flushing of the eye is used to normalize the PH, no current device exists to secure a flow system into the eye. Furthermore, in certain infectious emergencies it would be advantageous to have a comfortable system to allow for continuous infusion of antibiotic or other drugs onto the ocular surfaces.
In refractive surgery called Lasik, a device known as a microkeratome is used on the front surface of the eye to create a thin slice of tissue. This thin slice of tissue is folded back and the exposed inner surface of the cornea is lasered. The microkeratome is a mechanized device with an oscillating blade that is driven across the eye either manually or with a motor drive. The device is held on the eye by a vacuum ring that pulls the cornea up into the ring to come into contact with the blade. If the microkeratome contacts an obstruction during the pass it slows down or is deflected up. The result of slowing down or stopping is a wave on the surface to be lasered that can cause irregular vision. If the obstruction is hard enough, the ring can be dislodged and a partial flap is created usually leading to an aborted procedure. The most common cause of an obstruction is the microkeratome bumping into a lid speculum, especially in a tight eye. Thus a device to hold the lid open, without obstructing the microkeratome, would be particularly advantageous.
The lowest point in the eye when the patient is laying flat is the sulcus or the point where the clear covering of the eye folds back on itself around the globe. Conventional fluid removal systems do not adequately reach the sulcus because such systems are attached to the lid margin and tend to rise away from the sulcus when lids are spread open, especially when such systems are attached to a small lid.